The invention relates to a thin-film evaporator comprising a vertical drum, a supply line that is arranged in the upper region of the drum and is used to supply a medium to be evaporated, a heating jacket arranged on the periphery of the drum and forming vapours, a discharge line for discharging the residue left in the lower end of the drum, and a condenser supplied with a coolant.
Temperature-sensitive substances such as, for example, pharmaceutical solutions or food concentrates may be heated to the boiling point only temporarily. So-called thin-film evaporators in which the medium to be evaporated or the solution to be concentrated by evaporation, respectively, is applied to the evaporator area only as a thin film serve for meeting this demand. The result of this is just a short contact time with the heating surface so that thermally unstable liquids and substances, respectively, can also be used and are only exposed to a low evaporation temperature, in particular also under a vacuum or at a very low pressure. Furthermore, thin-film evaporators are used for separation tasks if the product accumulating as a residue has poor flow properties and/or is prone to agglutinations.
Thin-film evaporation processes are based on the principle of simple distillation according to which the separating capacity of said type of evaporator is limited. Thin-film evaporators are available in various designs, for example as falling-film evaporators or as rotary evaporators (known from Chemie Technik by Dr. Ing. Eckhard Ignatowitz, 5th edition, Europafachbuchreihe, page 306).